The centre, which recently set out how it built its new IT system using an agile approach, has now revealed further details of the architecture behind the system.

Its principle aim was to make as much use of Software-as-a-Service as possible, but in a blogpost, the centre’s chief architect, known as Richard C, said that there were some areas where the team didn’t feel they could do so comfortably.

The area the team felt most comfortable using SaaS was office productivity, because the security properties – and risks - are well understood, which meant they could be articulated to senior leadership.

Richard said that the NCSC had chosen Office 365 because it worked “in our context”. He stressed that this was “not an endorsement, or an assessment…that Office 365 is better” than G-Suite, which is the other office productivity platform it had published guidance for.

“We're also aware that Office 365 can be configured well, or poorly, so we've worked hard to configure the service to our liking and following our own guidance,” he said.

The centre said that for users, the basic steps they will need to access their email or productivity tools “are quite simple”: they authenticate to their device, connect to WiFi or 4G and then open their email applucation or use the internet to connect.

However, there were some areas that the NCSC said it “didn't yet have the knowledge or confidence we would have wanted to rely on SaaS”, which centred on underpinning security infrastructure on device management, user identity and trust infrastructure.

In these cases, the centre is using Infrastructure-as-a-Service services where there it “could rely on a strong security boundary”, and chose to build across two different IaaS offerings.

Meanwhile, the centre said that in order to get the service up and running quickly, users were limited to either a laptop or tablet running Windows 10 and those that needed smartphones had one running Apple iOS.

“We were careful in our initial choice of devices to ensure the hardware-based protections we wanted were available and easy to configure,” Richard said.

“We plan to expand our offerings a little to include other major platforms in due course.”